Could you be more specific? Which features would you like to see?
(Edit: it looks like you CAN turn it off in the settings.)
Here's some info on how it works if it helps address your concern: We've transformed the language generation problem into a labelling problem. From a systems point of view it's not any different from spam filtering, or tabbed inbox, and we use the exact same features. Smart Reply uses a whitelist of around 30k independently generated & sanitized phrases. You could think of each whitelist entry as a label. So when an email comes in on the delivery pipeline we just label things, like we've always done. We label (spam/not-spam) for spam filtering, we label (promo/social/update/forum) for tabbed inbox, and we label (Thanks!/Sounds good!/etc/etc) for smart reply.
Do you record what responses people choose? If so is that data used to personalize the responses or just stored in aggregate?
This was such a sneaky-good feature with Mailbox (before Dropbox shut it down) and solves a bulk of my priority / triage problems with email. I've surprisingly had a difficult time finding any other client that can do this.
...Though, knowing HN, I'm sure someone probably has one up their sleeve =)...
This allows me to have business actionables on top, then personal actionables, then unfiled bills, then new incoming messages.
I'm a huge fan of Mail.app, but my biggest frustration is that the colored flags don't carry to my iPhone (the latter of which only has one color flag in the Mail app.)
My other response is that I'm big on stack-ranking tasks / priorities, so your flow would be great for personal stuff, but not best for what I need for work.
You can also use 'super stars' to accomplish multiple priority states within starring.
Here's an example of a real power user: https://medium.com/@gregsramblings/how-i-tamed-gmail-at-work...